1. Field of the Invention
This invention generally relates to a combination weighing apparatus. More specifically, the present invention relates to a combination weighing apparatus that weighs a combination of articles based upon weight data from a plurality of weighing members.
2. Background Information
Combination weighing is generally desirable for its speed and accuracy. In combination weighing, the weight and number of articles received by each of a plurality of hoppers is measured by a load cell (a weight detector). The combined weights of each are calculated and a plurality of hoppers is selected to make a combined weight that is within a predetermined range of weights, and the articles from these hoppers are collected. This allows a collection of articles with a predetermined weight or a predetermined quantity to be obtained.
The present inventors have invented and applied for a patent on this type of combination weighing apparatus, which employs a construction in which article supply members (buckets) circulate to supply articles for each hopper to be weighed (Japanese Patent Application No. 2000-221871). The combination weighing device related to this invention rotates a plurality of buckets that collect articles loaded therein, and when a bucket comes to a position opposite one of the plurality of weighing hoppers that is empty, the articles in a bucket are dropped down into the weighing hopper. In other words, the buckets rotate above the weighing hoppers, and when there is an empty weighing hopper below, a bucket drops articles into the weighing hopper.
However, if a bucket conducts an article supply operation when there is an empty weighing hopper below it and other conditions are not taken into consideration, it tends to be difficult to supply articles to an empty weighing hopper that is positioned downstream of the direction in which the buckets are rotating. In other words, weighing hoppers on the downstream side are empty for a long time. When the number of empty weighing hoppers increases, the number of weighing hoppers that are included in combination weighing decreases. This produces problems such as a decline in combination weighing accuracy, or the combination weighting itself not being achieved.
In view of the above, there exists a need for a combination weighing apparatus which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
The object of the present invention is, in a combination weighing apparatus that supplies articles from article supply members that rotate with respect to a plurality of weighing hopper-type of weighing members, to prevent from occurring situations in which some of the weighing members cannot receive supply of articles easily, and increase combination weighting accuracy.
A combination weighing apparatus weighs a combination of articles based on weight data from a plurality of weighing members, the combination weighing apparatus comprising a plurality of article supply members, a rotation mechanism, and a controller. The plurality of article supply members each supply articles to any of a plurality of weighing members. The rotation mechanism rotates the plurality of article supply members so that the article supply members move along an arrangement of said plurality of weighing members in a weighing area. The weighing area is an area in which the plurality of weighing members are disposed. The controller controls the supply of articles from the article supply members in the weighing area to the plurality of weighing members. In addition, the controller selects from amongst the plurality of weighing members that request a supply of articles (hereinafter, article requesting weighing members), gives precedence to those weighing members that are downstream of the direction in which the article supply members move, and supplies articles thereto.
Here, when the article supply members that supply articles to the weighing members are rotated, and the article supply members enter into the weighing area, articles are supplied to the article requesting weighing members from these article supply members. Then, when articles are supplied to the article requesting weighing members from each article supply member in the weighing area, the controller supplies articles such that it gives precedence to the article requesting weighing members that are downstream.
In contrast to the situation in which the control of the supply of articles from the article supply members occurs when opposing weighing members request a supply of articles, because this type of control is achieved, problems such as the supply of articles to the article requesting weighing members not occurring despite the fact that a supply of articles was requested are prevented.
In other words, when article supply to weighing members unconditionally occurs in a supply system that circulates in one direction, the further downstream the weighing members are, the more difficult it becomes to supply articles to them. When this situation continues, there is a danger that the rate of productivity of the combination weighing apparatus might decrease because articles fail to be discharged properly. This sort of problem can be prevented in the present invention.
In addition, the rotation mechanism may circulate each article supply member in a horizontal plane, and may also circulate them such that they are perpendicular to each other. Further, the rotational path may be circular, oval, or elliptical.
Preferably, in the combination weighing apparatus, the rotation mechanism moves the plurality of article supply members such that the plurality of article supply members rotate between the weighing area and an article loading area. The article loading area is an area in which articles are loading into the article supply members.
Here, article supply members that have had articles loaded therein in the product loading area rotate to the weighing area. In the weighing area, article supply takes place from the article supply members to the article requesting weighing members such that the downstream article requesting weighing members take precedence.
Thus, because a construction is adopted in which articles are loaded into the article supply members in the article loading area, an automated weighing line can be easily designed. In addition, when articles are manually placed into the article supply members, the task of doing so is made easy because the location where this operation takes place is fixed in the article loading area.
Preferably, in the combination weighing apparatus, the controller, from amongst the plurality of weighing members that request article supply, controls the weighing members in order, starting with the weighing member that is furthest downstream in the direction in which the article supply members move.
Here, when the priority of article supply with respect to each weighing member is equal, product supply is difficult to perform in order. In other words, control occurs starting with the weighing member that is furthest downstream. Because of this, it is easy to place a large number of weighing members in a position in which they can be supplied with articles.
Preferably, in the combination weighing apparatus, the controller associates one article supply member capable of article supply with one weighing member that requests article supply. The associated article supply members includes the position opposite the weighing member that requests a supply of articles, the article supply member that is as close as possible to the upstream side in the direction of movement from that position, and the article supply members that are capable of supplying articles.
Here, the article supply members are associated in turn, beginning with the article supply member furthest downstream.
In addition, other than the article supply members that are actually confirmed to have articles placed therein, article supply members capable of supplying articles also includes article supply members in which it is presumed that articles have been placed therein.
Preferably, in the combination weighing apparatus, when there is a weighing member requesting a supply of articles in a position opposite an article supply member capable of supplying articles, the controller controls as below. If [N1] is less than or equal to [N2], articles are supplied from the article supply member that is in the position in front of the opposing weighing member to the opposing weighing member, and if [N1] is not less than or equal to [N2], articles are not supplied from the article supply member that is in the position in front of the opposing weighing member to the opposing weighing member.
[N1] represents weighing members that request a supply of articles, and is the number of such weighing members that are present from furthest downstream to the opposing weighing member. In addition, [N2] represents article supply members that are capable of supplying articles, and is the number of such article supply members that are present from the position of the weighing member that requests a supply of articles furthest downstream to the position of the article supply member in the position in front of the opposing weighing member.
Further, other than article supply members that are actually confirmed to have articles placed therein, article supply members capable of supplying articles includes article supply members that are presumed to have articles placed therein (article supply members that are not confirmed to be empty).
Preferably, in the combination weighing apparatus, each time the controller moves the plurality of article supply members only one fixed pitch of the plurality of weighing members, the controller repeats control of the supply of articles from the article supply members in the weighing area to the plurality of weighing members.
Here, because the aforementioned control is repeated each time the article supply members are moved one pitch, the most recent conditions can be quickly reflected in the control, such as the weighing members that have discharged articles in the combination weighing changing to weighing members that request a supply of articles, and weighing members changing to weighing members that request additional supplies.
Preferably, in the combination weighing apparatus, the controller, based upon combination weighing, sets the rotation cycle of the rotation mechanism to be faster than the article collection discharge process cycle of predetermined weighing members.
Here, in order to reduce the number of weighing members that cannot participate in combination weighing due to a lack of article supply, the rotation cycle of the article supply members is faster than the article collection discharge cycle. In this way, the incremental speed of the supply of articles by article supplying members and the weighing members that can participate in combination weighing can be prevented from dropping below the incremental speed of the discharge of articles and the weighing members that cannot participate in combination weighing.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.